RELATIONSHIPS AMONG LIVER AND KIDNEY VOLUMES, LEAN BODY-MASS AND DRUGCLEARANCE

Aims To determine whether lean body mass (LBM), a possible surrogate o f liver and kidney volumes, correlates with hepatic and renal drug cle arances. Methods Twenty-one disease-free patients with a history of ca ncer and with normal hepatic and renal function were studied. Salivary pharmacokinetics of oral antipyrine (1200 mg) and 24 h creatinine cle arance were determined following the determination of LBM by dual ener gy X-ray absorptiometry and the determination of liver and kidney volu mes by helical CT scanning. Results Liver volume correlated with LBM ( r(2)=0.21, P=0.04%, body surface area (BSA) (r(2)=0.54, P<0.001), and total body weight (TBW) (r(2)=0.61, P<0.001). Kidney volume correlated with LBM (r(2)=0.49, P<0.001), BSA (r(2)=0.43, P=0.002) and TBW (r(2) =0.24, P=0.03). Stepwise multiple regression analysis, incorporating t he independent variables of age, height, weight, sex, BSA, LBM, alcoho l consumption, smoking status and liver volume and the dependent varia ble antipyrine clearance, indicated that LBM was the only independent correlate of antipyrine clearance. A stepwise multiple regression anal ysis with kidney volume in the independent variables, and creatinine c learance as dependent variable, showed that kidney volume and age were the only independent correlates of creatinine clearance. A nomogram u sing serum creatinine and LBM was comparable with the Cockcroft and Ga ult nomogram in calculating creatinine clearance. Conclusions Of the a nthropometric variables tested, LBM was the only determinant of antipy rine clearance, but this was not due to a relationship between LBM and liver volume. By contrast, the relationship between creatinine cleara nce and LBM appeared to be due to a relationship between LBM and kidne y volume.